Method of making a reinforced hollow plastic article of wrapped tapes of fibrous material



1967 H. M. RICHARDSON ETAL 3,351,509

METHOD OF MAKING A REINFORCED HOLLOW PLASTIC ARTICLE OF WRAPPED TAPES OFFIBROUS MATERIAL Original'Filed Dec. 28, 1962 16 Sheets-Sheet 1 Y. w m4% E w W N n v N I I me Q A Pnk Z? a w wow Ev w 22 f -6 "F 3 as M c F\ M.M0EY.W F L w if Q q 5 5 am 6% Maw 9% -5 Qw 5 W wmm mow H9; F L r1.!L FlY 60% mu m 0m mm w m B OO mmwum Nov. 7, 1967 METHOD Original Filed Dec.

.RICHARDSON ETAL 3,351,509 REINFORCED HOLLOW PLASTIC ARTICLE 0!" HM OFMAKING A WRAPPED TAPES OF FIBROUS MATERIAL 28,

1962 16 Sheets-Sheet 2 k0 F250 5. WILEY WESLEY s. LnQso/v HTTY Nov. 7,1967 H. M. RICHARDSON ETAL 3,351,509

METHOD OF MAKING A REINFORCED HOLLOW PLASTIC ARTICLE OF WRAPPED TAPES OFFIBROUS MATERIAL Original Filed Dec. 28, 1962 16 Sheets-Sheet 3INVENTORS Nov. 7, 1967 H. M. RICHARDSON ETAL 3,351,509

METHOD OF MAKING A REINFORCED HOLLOW PLASTIC ARTICLE OF WRAPPED TAPES OFFIBROUS MATERIAL Original Filed Dec. 28, 1962 16 Sheets-Sheet 4 Nov. 7,1967 METHOD OF MAKI Original Filed Dec.

H. M. RICHARDSON ETAL NG A REINFORCED HOLLOW PLASTIC ARTI WRAPPED TAPESOF FIBROUS MATERIAL INVENTOR5 HENRY M P/cHfleaso/v F D E. WILEY W/ EsLEv s. LH

Nov. 7, 1967 H. M. RICHARDSON ETAL 3,351,509

METHOD OF MAKING A REINFORCED HOLLOW PLASTIC ARTICLE OF WRAPPED TAPES OFFIBROUS MATERIAL Original Filed Dec. 28, 1962 16 Sheets-Sheet 6INVENTORS HENRY M. ICHQRDSOAJ HLFQED C GH/M/ ea @EsLEv s LQESOAL f/ m BYWZM HTTY.

1967 "H. M. RICHARDSON ETAL 3,351,509

METHOD OF MAKING A REINFORCED HOLLOW PLASTIC ARTICLE OF WRAPPED TAPES OFFIBROUS MATERIAL Original Filed Dec. 16 Sheets-Sheet 7 HfTY.

1967 H M. RICHARDSON ETAL 3,351,509

METHOD OF MAKING A REINFORCED HOLLOW PLASTIC ARTICLE OF WRAPPED TAPES OFFIBROUS MATERIAL Original Filed Dec. 28, 1962 16 Sheets-Sheet s L\ \1 oQM H N 2&2 F

INVENTOR5 MEN/2v M P/c/mepsom 14L FEED C.HLBEE6H/N/ F250 5. W/LEY WESLEY5, LHESOA/ Nov. 7, 1967 H. M. RICHARDSON ETAL 3,35 ,50

METHOD OF MAKING A REINFORCED HOLLOW PLASTIC ARTICLE OF WRAPPED TAPES OFFIBROUS MATERIAL Original Filed Dec. 28. 1962 16 Sheets-Sheet 9INVENTOR5 HENQY M P/cHmwso/v HLF/QED C HLBERGH/N/ FRED E WILEY WESLEY sLQE'SQN Nov. 7, 1967 H. M. RICHARDSON ETAL METHOD OF MAKING A REINFORCEDHOLLOW PLASTIC ARTICLE OF WRAPPED TAPES OF FIBROUS MATERIAL OriginalFiled D60. 28, 1962 16 Sheets-Sheet 10 FRx IOO Z01:

QESISTANCE 4o Fe x IOO OF PHEDSTAT QOTATION INVENTORS HENEY ME/cumzoso/v HLFRED c. flLBE$6HlNl FRED E. was

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Nov. 7, 1967 H. M. RICHARDSON ETAL METHOD OF MAKING A REINFORCED HOLLOWPLASTIC ARTICLE Ob WRAPPED TAPES OF FIBROUS MATERIAL Original Filed Dec.1962 16 Sheets-Sheet 11 M M w O T mwaY Q w e mwfi wz xv v 5 mm v 9mm /EWNW Y0 E. $0 M 7% rmmw v a Nov- 7, 1967 H. M. RICHAFIQDSON ETAL3,351,509

METHOD OF MAKING A REINFORCED HOLLOW PLASTIC ARTICLE OF WRAPPED TAPES OFFIBROUS MATERIAL Original Filed Dec. 28, 1962 16 Sheets-Sheet 12 1 45/FEED 5Z5 DRIVE TIMER CLUTCH 5'55 TIMER BRAKE357 k W CLUTCH PULLER CLUTCH 407 INVENTIORS F/EMQY M. E/CH/QRD5OA/ QLFIPED C. HLBEQGHI/V/ FRED5.. W/LEg WESLEY 5 L147 so v NOV. 1967 H. M. RICHARDSON ETAL 3,351,509

METHOD OF MAKING A REINFORCED HOLLOW PLASTIC ARTICLE OF WRAPPED TAPES OFFIBROUS MATERIAL Original Filed Dec. 28, 1962 l6 Sheets-Sheet 13INVENTORS HEA/PY M4 Elcl-mQoso/v HLFPED HLBEQGH/N/ FEED IL H. M.RICHARDSON ETAL Nov. 7, 1967 METHOD OF MAKING A REINFORCED HOLLOWPLASTIC ARTI WRAPPED TAPES OF FIBROUS MATERIAL Original Filed Dec. 196216 Sheets-Sheet 14 INVENTORS CHflEDSON E. WILEY WESLEY 5. LQPSOA/RICHARDSON ETAL 3,351,509 REINFORCED HOLLOW PLASTIC ARTICLE OF TAPES OFFIBROUS MATERIAL l6 Sheets-Sheet l5 ATTY.

WRAPPED METHOD OF MAKING A mdw Nov. 7, 1967 Original Filed Dec.

W T 5 N wow 0 mmm wfm v ff Z 5W W M M #4 D H w YEDL W 3? EL H FW 1967 H.M. RICHARDSON ETAL ,5

METHOD OF MAKING A REINFORCED HOLLOW PLASTIC ARTICLE OF WRAPPED TAPES OFFIBROUS MATERIAL Original Filed Dec. 28, 1962 16 Sheets-Sheet l6 mR mkma mt ENM W W m w N W mg w W 5 2% mi mR Y M QR QT, m& M? e 5 x m 5 wok Mz 0 5 WED/.fl mfg um m m u 1 0 0R was 5 T E Q ,,A/// /r g J 4 /J////Q7772Z 3 g k W ,1 /./w//; 11/ r/ 1 z, ///X/// J V/// //x/////////w35E? h i '4 w mdu TQM 00h W MR ROB United States Patent Ofiice 3,351,509METHOD OF MAKING A REINFORCED HOLLOW PLASTIG ARTICLE OF WRAPPED TAPES OFFIBROUS MATERIAL Henry M. Richardson, Somers, Conn, Alfred C. Alber-Fred E. Wiley, Long- This is a divisional application of our copendingapplication Ser. No. 248,058 filed Dec. 28, 1962, now Patent No.3,256,128.

This invention is a method and apparatus for making a reinforced hollowplastic article and, while adapted for the fabrication of articles ofdifferent kinds and for different uses, is of outstanding utility in themanufacture of pipe formed from wrapped strips and/or tapes of fibrousmaterial in which tapes are incorporated reinforcing glass strands whichextend parallel to one another and to the lateral edges of the tapes.

The primary objects of this invention are to produce a non-metallic pipehaving an impervious, corrosion-resistant plastic lining encased withinresin impregnated fibrous tapes having longitudinal reinforcing strands,with right and left hand wrappings of reinforced tapes under balancedcondition and to provide such a pipe by including, in its manufacture,molding and curing steps which stretch or tensilize each layer of thewrappings in turn, so that all of said reinforcing strands are broughtto the same degree of tension, with the result that, when internal fluidpressure is applied to the pipe in use, stresses thereon are carried byall reinforcing strands equally.

In carrying out this invention, a mandrel, composed of successivesections, detachably joined end to end, is caused to travel along apredetermined path. As it so travels, there is first applied to themandrel a helically wound liner. This liner is applied to the mandrel ata first winding station embodying two winding heads arranged to rotateabout mandrel and to supply to the latter a liner consisting of twoplies of a suitable corrosionresistant material, such as unplasticizedpolyvinyl chloride strips helically wound in the same direction with oneply overlying the other and with the edges of each ply abutting oneanother, in such manner as to break joints with the abutting edges ofthe underlying layer.

The first ply of the liner applied to the mandrel has been previouslycoated on the outside, to contact the second ply, with a thin film of acombination of a phenol resin and an acrylonitrile-butadiene syntheticrubber (Buna-N). This layer of adhesive is previously laid down from anethyl acetate solution. The solvent is then dried and the adhesive lefton the polyvinyl chloride strip surface in such condition that it issubstantially non-tacky, but will adhere to itself under pressure.

The second layer of liner strip of the same kind, Wound on the mandrel,has a coating of vinyl resin polymer adhesive on its surface wi ichengages With the first layer of vinyl strip. The function of theadhesive film is two-fold. Its first function is to act as a pressuresensitive adhesive to hold the two layers of polyvinyl chloride strip inthe preform until the latter is subsequently molded, as hereinafterdescribed. Also, during the molding operation, the preform is internallyexpanded and the adhesive cured and thermoset to form a tenacious bondbetween the liner layers.

After the liner has been applied to the mandrel as stated, there is nextapplied over said liner, at successive E,Ii5l,5d9 Patented Nov. 7, 1967plurality of layers or plies of resin impregnated highly absorbentpaper, such as Kraft, or asbestos, carrying on its surface parallel laidreinforcing fibers, preferably of glass. This overlay consists of afibrous web of paper or asbestos fibers in strip form and impregnatedwith a solution of a curing, thermosetting resin, e.g., phenolic orepoxy resin, combined directly with parallel laid glass fiber strands inthe form of a sheet or beam. In practice this beam may consist of from60 to glass strands per inch of width. The combined strip, comprisingthe fibrous web with the glass strands laid on it, is then passedthrough a drying oven and is conditioned to have the proper flow andcure characteristics to produce the end product cured plastic pipe, Thereinforced web is then slit to a Width such that when it is helicallywound on a mandrel with a helix angle, which is determined by thedesired distribution of circumferential and longitudinal elongationcharacteristics of the finished pipe, will wind Without overlap andwithout leaving a gap. Therefore, each individual helical wrap forms acontinuous tubular element ply in the wall of the pipe.

The fibrous web to which reference has been made may, if desired, embodyasbestos fibers prepared in accordance with the disclosure of US. PatentNo. 2,626,213 granted to I. I. Novak, used according to said disclosureor in combination with randomly oriented glass or other fibers.

The process of making the pipe from this prepared and slit tape is oneof continuous winding on mandrel sections which are successivelydetachably coupled to one another and fed in continuous successionthrough the continuous wrapping machine of this invention. The assembledmandrel sections may be of any desired length, e.g. 20 ft., and they maybe of any desired diameter. They are successively coupled together endto end and are fed to and through the machine by a pushing or feedingunit which propels them through several Winding stations during thewrapping operations to which reference has been made. At thesesuccessive stations, progressive winding stands are constituted toalternately feed the glass rein forced tapes in opposite directions orhand and auto-- matic mechanism .is provided to maintain each of thetapes at all times under uniform tension so that, even in the finishedpreform, the tension on all of the tapes is uniform and balanced.

After the preform has been completed on any particular section ofmandrel, this preform is severed at a mandrel coupling by rotatingknives and said preform, with the mandrel section therein, is moved freefrom the following mandrels and windings and discharged from themachine. The mandrel section container in such preform is then removedfrom the preform and the latter is subjected to a molding, tensioningand curing operation in the presence of sufficient heat to thoroughlycure the resins therein contained and produce ahomogeneous construction,with the reinforcing glass fibers of the several layers or plies under atensilized balanced condiiton. Maximum circumferential and longitudinalstrength of the pipe results. In such a pipe, the pressure of fluidspassing through such pipe will be borne equally by all plies or layersof the pipe.

In addition to the foregoing steps of this process, provision may bemade for the coupling together of successive lengths of pipe sections toform a continuous conduit in the field or plant where they are installedfor use.

Features of this invention, other than those averted to, will beapparent from the hereinafter detailed description and appended claims,when read in conjunction with the accompanying drawings.

The accompanying drawings illustrate one practical emstations, a

bodiment of the invention, but the construction therein C3 shown is tobe understood as illustrative only, and not as defining the limits ofthe invention.

FIGS. 1 and 1A collectively constitute a pictorial side elevation ofapparatus embodying the present invention.

FIG. 2 is an exploded perspective view, partly in section, of couplingelements used to secure in axial alignment successive mandrel sectionson which the pipe is formed.

FIG. 3 shows said coupling elements in assembled relation, partly incentral section and partly in elevation.

FIG. 4 is a section on the line 44 of FIG. 3.

FIG. 5 is a diagrammatic showing of the main drive mechanism of thestructure shown in FIGS. 1 and 1A.

FIG. 6 is a perspective view showing the mechanism for advancingassembled successive mandrel sections through the greater portion of thelength of the machine.

FIG. 7 is a transverse section on the line 77 of FIG. 6, showing meansfor gripping and feeding the assembled mandrel sections in succession asthey pass into and through the machine.

FIG. 8 is a perspective view of the parts shown in FIG. 7.

FIG. 9 is a perspective view of one of the Winding stands, theduplication of certain parts thereof being omitted in the interest ofclearness.

FIG. 10 is a plan view of one of said winding stands with certain partsomitted.

FIG. 11 is a vertical section on the line 1111 of FIG. 10.

FIG. 12 is a fragmental elevation looking in the direction of the arrow12 in FIG. 10.

FIG. 13 illustrates a rheostat employed to control the tension of thetapes as they are wound on the mandrel.

FIG. 14 is a graph illustrating the characteristics of the rheostat ofFIG. 13 during the functioning thereof.

FIG. 15 is a wiring diagram of the tape tensioning aspect of thisinvention.

FIG. 16 is an exploded view of cut-off mechanism whereby successivelengths of the formed pipe are cut from the following portions toproduce a preform after a pipe section has been fully wound and while itcontinues to travel.

FIG. 16A shows one of the cutter and cam arms of the assembly shown inFIG. '16.

FIG. 17 is a wiring diagram for the cut-off mechanism shown in FIG. 16.

FIG. 18 is a fragmental perspective showing mechanism for separating apreformed section of pipe, with mandrel section therein, from thefollowing pipe and mandrel sections after such preformed pipe has beensevered by the mechanism shown in FIG. 16. This view also showsmechanism for discharging the preform and the enclosed mandrel sectionfrom the machine.

FIG. 19 is a detailed view showing the operation of the pulling jawsshown in FIG. 18.

FIG. 20 is a side elevation of mechanism for supporting and registeringthe mandrel and partially wrapped pipe thereon with each successiveWinding stand of the machine as they leave the preceding stand.

FIG. 21 is a section on the line 2121 of FIG. 20.

FIG. 22 is a section on the line 2222 of FIG. 20.

FIG. 23 is a longitudinal view, partly in section and partly inelevation, showing the manner of removing a coupling part from one endof a mandrel section.

FIG. 24 is a like view showing the manner of removing a mandrel sectionfrom a preformed pipe previously formed thereon, to ready the preformfor the final molding and curing operations.

FIG. 25 is a cross section on the line 2525 of FIG. 24.

FIG. 26 is a longitudinal section of one end portion of the molding andcuring elements for the preformed pipe.

FIG. 27 is a cross section on the line 27-27 of FIG. 26.

FIG. 28 is a cross section of the line 2828 of FIG. 26.

FIG. 29 is a side elevation of the mold as it appears when ready tocarry out its functions.

The several successive mechanisms or stages for producing the preformedpipe of this invention are bracketed in FIGS. 1 and 1A of the drawingsand respectively designated 100, 200, 3% and 4110. They will behereinafter individually described in this order.

Prior to the feed of the mandrel sections M to the mechanism of Stage1110, they are detachably secured end to end by a novel form of couplingshown in FIGS. 2, 3 and 4. Each of these couplings embodies two parts,namely, a male part 1 and a female part 2. To accommodate this couplingthe opposite ends of each of the mandrel sections are interiorlymachined to a true cylindrical end portion coaxial with the exteriorsurface of the section and across the hollow interior of this machinedportion extends a pin 3.

The male part I is, in the main, cylindrical, but one end has a reducedshank 4 to provide what may be referred to as a clothespin projectionhaving a reentrant mouth 5 at the base of which is formed an angularlydisposed hole 6. When this clothespin projection is introduced into theadjacent end of a mandrel section and given a slight rotary turn, thepin 3 will move into the hole 6 and thus lock the male part to that endof the mandrel section after the manner of a bayonet joint, as seen inFIG. 4. In order to insure concentricity between the mandrel and themain portion of the male part, said male part is provided at the base ofthe clothespin projection with a land 7 of the same external diameter asthe machined internal diameter of the mandrel section M. The distant endof the female part 2 is formed with a clothespin projection 4 and hole 6corresponding to the like portions of the male part and adapted toengage with the pin 3 of its adjacent mandrel section M.

The contiguous ends of the two coupling parts 1 and 2 are respectivelyprovided with a slip connection embodying a lug or tang 8 and a socket 9to receive said lug in fairly close fitting relation. The ing 8 is shownas square, although it may be of any polygonal cross section. Said lug 8may, if desired, be provided therein with a hole 10 containing a springpressed ball detent. The walls of the socket may also be formed withalined holes 11 to detachably receive the ball. The tang and base of thesocket both have coaxially tapped holes 12, which are useful ashereinafter described in the withdrawal of the coupling parts from thepreform prior to withdrawal of the mandrel.

An important feature of this invention resides in the provision on thecoupling of a relatively soft external surface. This is preferablyaccomplished by reducing the adjacent end portions of the parts 1 and 2as shown at 13 and fitting tightly upon these reduced portions sleeves14 of some relatively soft material against which cutting rolls may actin cutting a completed preform from the preceding windings after eachpreform has been completed.

As hereinafter described, this cutting of the preform is initiated by asensing device (e.g. Westinghouse Proximity Limit Switch), the operationof which is controlled by the effect of different materials upon aninductive field. In order to so function, such a difference is dependentupon the passage of a magnetic or non-magnetic part in proximity to thesensing device. If the mandrel sections have magnetic characteristics,the parts 1 and 2 of the coupling have non-magnetic characteristics andthe sleeves 14 must also have nonmagnetic characteristics. In practiceit is preferred to make the mandrel of steel, the main parts of thecoupling of aluminum, and the sleeves 14 of a non-mangetic resin, such,for example, as polyethylene. With this relation between the parts, thesensing device is so constituted that it will react when the couplingspass in approximately thereto to actuate the severing iechanism ashereinafter described in detail.

As the mandrel sections are successively coupled together as stated,they are fed as a complete mandrel to the machine shown in FIGS. 1 and1A. It is essential that the sections be close coupled for, if any tangis not fully seated in its cooperating socket 9, a void will be leftbetween the contiguous ends of the parts of that coupling. This wouldcause difficulty during the passage of the mandrel through the machine.Consequently a feeler finger 101 (FIGS. 1 and 6) is positioned to bearagainst the mandrel as it is fed. If this finger feels any void in themandrel, it operates a switch to stop the machine.

Stage 100 (FIGS. 6, 7 and 8) The function of this stage is to grip themandrel fed thereto and push it through the stages of the machine up tothe point where a finished preform is cut from the following windings.To accomplish this function, there is provided in this stage a series ofmandrel engaging clamps 102.

Each of these clamps 102 is mounted on a carrier 103 which is in turnsecured to an endless chain 104. This chain passes around directionalsprockets S and is driven by a drive sprocket 106 which is supported ona shaft 107 journalled in side rails 1118 of this unit of the machine.The sprocket shaft 107 is driven through a sprocket 1119 and chainconnection 110 (FIG. 5) from a right angle gear reducer which is in turndriven from a gear box 17, belt driven from the adjustable speed motor16 which constitutes the prime mover for the machine.

Each clamp 102 embodies two arcuate clamping jaws mounted for openingand closing movement on a pin 111 (FIGS. 7 and 8) which supports thejaws on its carrier 103. The opposite sides of the carrier extenddownwardly and mount guide wheels 112 (FIG. 7) which ride on lowertracks 113 carried by the side rails 108. Above these lower tracks 113are upper tracks 114, the lower edges of which form with the lowertracks 113 longitudinal runways 115 (FIG. 8) in which the wheels 112travel to keep the clamp from tilting, whereby the clamps 162, whenclosed, travel coaXially with the mandrel.

Mounted to travel on each of the upper guides 114 is a Wheel 116, whichis mounted upon one end of a toggle arm 117, the other end of which issecured to a toggle lin'k 118 by a pivot pin 119. The distant end ofeach toggle link is pivotally secured in a slot 120 to a lug 121 rigidwith one jaw of the clamp. An adjusting screw 122 acts upon the upperpivot pin of the toggle link 1118 to adjust the throw of the toggle andthe pressure exerted by the jaws on the mandrel. Springs 123 normallybreak the toggle from the stressed position which it assumes when thecorresponding jaw of the clamp is in closed position. The togglearrangement described is duplicated on both sides of the carrier, thetoggle arm 117 in each case being supported on a pivot pin 124. When thetoggles are in the stressed position shown in FIG. 7, the jaws arefirmly closed upon the mandrel at the point where the latter passesthrough each clamp.

In order to insure a firm grip upon the mandrel and insure positivepushing action by the several clamps, the jaws of each clamp arepreferably provided with a cast iron liner 125. With the gripping actionproduced by such a liner, there is no slippage between the severalclamps and the mandrel. In practice, the inner radius of each jaw isslightly different than the outer radius of the |mandrel so thatdeflections resulting from the toggle action will assure accurate matingfriction surfaces between said jaws and the mandrel.

The operation of the machine of this invention has demonstrated thatspecial means must be provided for bringing the clamps in successioninto cooperation with the mandrel, otherwise there is a probability thatthe clamp sections, when brought into position to engage the mandrel,will strike the same and throw the mandrel out of line. This will causetrouble in the subsequent operations of the machine. This difficulty hasbeen overcome by the particular formation of the wheel supportingsurfaces of the lower and upper tracks 113 and 114. The lower track maybe flat throughout so that, as the chain advances each clamp carrier103, the Wheels 112 of such carrier will first be raised to the level oftrack 113 and proceed to travel along the same.

It is essential as a protective measure against damage to the parts thatthe clamps be fully opened as they approach engagement with the mandrel.In order to insure this, there is mounted at the forward end of themachine camming members 116a (FIG. 6) so placed that, as the carrier 103passes from the lower path of its travel to the upper path thereof,these camming members 116a will lie in the path of the toggle wheels 116of any clamp which may be closed at that time. The engagement of thewheels 11-6 with these camming members 116a will open such a clamp andprepare it to properly cooperate with the mandrel.

Moreover, the clamp on each carrier .must not be closed until themandrel has entered the confines of the clamp. To insure this, the lefthand or leading end of each upper track has (FIG. 8) an abrupt slopingportion 126 merging into a portion 127 of less slope which, in turn,merges into the flat surface of the upper track 114.

Simultaneously with these operations, the toggles, which approach thetracks 114 in broken, i.e. open position, first engage their wheels 11%with the abrupt inclination 126 of the upper track to partially closethe gripping jaws, while the less sloping portion 127 of the upper trackcompletes the closing of the jaws as the axis of the clamp comes intosubstantial registration with the axis of the mandrel. Meanwhile theupper reach of chain 104 is supported on slide 131 (FIG. 7). Experiencewith this construction has shown it to be thoroughly reliable for itinsures proper gripping of the mandrel without any tendency to throw thelatter out of line.

As the toggle wheels 1116 ride up over the inclined portions 126 and 127in succession, they will move the toggle arms in directions to close theclamping jaws upon the mandrel and these jaws will be finally closed bythe time these toggle wheels 116 arrive at the fiat horizontal portionsof the upper surfaces of the upper tracks 114.

This relation between the parts persists while each clamp travels alongsaid upper horizontal surface of the upper track 114, to push themandrel forwardly until the toggle wheels 116 come to the opposite endsof both tracks. These opposite ends are shown in FIG. 8. Each uppertrack is there stepped down, as shown at 128, and into thesestepped-down portions, the wheels descend, assisted in such descent byknock-down pins 12?. The descent of these wheels is sufiicient to throwthe toggles over dead centers, i.e., break the toggles, at which timethe springs 123 will cause the toggles to be fully broken to open thejaws of the associated clamp.

By continued movement of the carrier, the wheels 116 will leave thetracks, to be carried by the chain 104 in a retrograde direction at alower level to the point of starting. During this return movement, thewheels 112 will be guided to starting position by lower guides 130 (FIG.7) which will preclude undue sagging of the chain. Also during returnmovement, the springs 123 will hold the toggles in broken condition andthe clamps open until the operations described with respect toengagement of the clamps with the mandrel are repeated.

Stage 200 (FIGS. 9-15) As the mandrel is pushed along a rectilinear pathby the clamps 102, it passes through a plurality of winding stands whichmay be of any desired number, depending upon the wall thickness andconsequent strength of the desired end product pipe. During its passagethrough the first stand, there is applied to the mandrel a pipe liner,comprising at least one ply of, e.g., unplasticized polyvinyl chloride.As it passes through succeeding winding stands, there is applied overthis pipe liner successive layers or plies of the preferably glass fiberreinforcing tapes of the character hereinbefore described.

FIGS. 912 of the drawings show one of these stands, the others being ofidentical form except that the several consecutive stands are soconstituted as to wrap the glass reinforced tape in alternate directionsor hands, i.e., With right and left hand helices, respectively. In thestands which wrap the glass reinforced tapes, provision is made for thetaking up of an interleaf of any suitable character which is positionedbetween the successive convolutions of the coiled strips of such tapes.The purpose of this interleaf is to preclude successive convolutions ofthe tape from sticking to one another in such manner as to interferewith the proper feed of the tape to the mandrel. In the stand whichfeeds the unplasticized polyvinyl chloride strips, an interliner is alsoused where these strips have an adhesive backing.

As shown generally in FIG. 9, each stand comprises a pair of spacedapart upright frames 201 and 202. Journalled for rotation in hearings onthe frame 201 is a sprocket 203 and similarly journalled for rotation atthe inner side of the frame 202 is a plate 204. The sprocket and plateare rigidly secured in spaced relation by spacer bars 205 and 206 which,together with the sprocket and plate, form a rotatable winding head.

Mounted on one side of the spacer bar 205 is a pivot block 207 carryinga pivoted arm 208 which serves as a support for a roll 209 of linerstrip or reinforced glass tape T, as the case may be. It is from thiscoil that the liner strip or tape is fed to the mandrel as the Windinghead rotates about the latter in such a manner as to lay the strip ortape on the mandrel in a helical path with the strip or tape from thatparticular roll in edge abutting relation to form one layer or plythereof on the mandrel. The pivot block 207 is mounted for adjustmentlongitudinally on the bar 205 so as to obtain proper correlation of theedge abutting joints of the successive layers of strips and tapes.

The several winding heads are all driven from a winder shaft 18 (FIGS.and 9) having a chain drive from main drive shaft 19 which has a chaindrive connection 20 with shaft 21 driven from the gear box 16. Shaft 13drives a plurality of variable speed and directional units 210, so thattheir output spindles 211 rotate in one direction, and also drivesinterspaced variable speed units 210a, so that their output spindles 211and 211a rotate in the opposite direction. The output spindles of eachof these units have a chain drive connection 212 (FIGS. 5 and 9) withthe gear 203 of one of the winding heads, whereby the several heads aresuccessively rotated in opposite directions. The speed and direction ofrotation of the winding heads of the several stands is controlledthrough these conections, so that the winding may take place at thedesired speed and .in right or left hand windings, as is required forthe respective stands.

In FIG. 9 only one arm 208 and tape roll are shown as adapted to applyone layer or ply of the strip to the mandrel. However, FIGS. 10 and 11show that the same identical structure is applied to the opposite faceof the bar 206, so that two layers of liner strip or tape will beapplied at each stand with these two layers overlapping one anotherone-half the width of the previous strip or tape thus fed. The edgejoints between each second layer or ply will thus overlie substantiallythe medial line of the underlying ply or layer.

In accordance with the present invention, the several strips of theliner and reinforced tape are fed under predetermined uniform tension.In order to accomplish this, due provision must be made for the decreasein the diameter of the rolls as the strips and tapes are fed from saidrolls. The means for accomplishing this result will next be described.

Rigidly supported on each arm 208 are a pair of parallel rods 213extending in one direction, while another pair of parallel rods 214extend in the opposite direction from said arms (FIGS. 9 and 12). Fixedon the rods 213 is a supporting block 215 and on this block is pivoted atoothed quadrant 216. The teeth of this quadrant mesh 8 with a pinion217 secured to the spindle 218 of a rheostat shown in FIG. 13.

Rigid with the quadrant 216 is a rod 219 which carries at its far end afollower roller 220 biased by a spring 221 to at all times engage witheach of the strip and tape rolls 209. Fixed to the spindle 218 of therheostat is an arm 222 mounted to travel over a variable resistanceelement 223 in the form of an arcuately disposed coil. This coil isWound spirally around an insulating toroid or ring with one endconnected to a conductor 224. This conductor leads to a magnet 225 whichacts upon a friction brake 226 (FIG. 10) associated with the spindle 227on which a roll 209 is mounted and locked against rotation thereon byhandle-operated eccentrics 228 (FIG. 12). By varying the current flowingthrough the friction brake, which may be any appropriate conventionalform, the amount of friction applied to the spindle of the roll 209 iscontrolled to place the desired tension on the strip or tape T fed tothe mandrel.

The wiring diagram of FIG. 15 shows very clearly how the parts describedare electrically connected and controlled to accomplish a uniformtension on the respective strip or tape coils of each winding head asthe strip or tape is fed therefrom to the mandrel.

According to this diagram (FIG. 15), 550-volt, 3- phase, 60-cyclealternating current power is supplied to the entire machine throughconductors 229, 230 and 231. Fuses 232 give overload protection, and3-pole switch 233 is provided to disconnect power from the main drivemotor 16 on the machine. Conductors 234 and 235 receive SSO-volt,60-cycle, single-phase power from one phase of the SSO-volt, 60-cycle,3-phase power which is supplied to the machine. Transformer 236 reducesthis single-phase, 550-volt power to volts, single phase. Relay 237 isprovided with a start button 238 and a stop button 239 so that this120-volt, single-phase power may be supplied to autotransformer 240 ormay be disconnee-ted from this autotransformer should occasion require.Autotransformer 240 is used to adjust the tension on the entire machinefor starting and operating levels. It also supplies an alternatingvoltage adjustable from O to volts to transformer 241, which furtherreduces the adjustable alternating voltage from 0 to 140 volts to 0 to34 volts. Conductors 242 and 243 carry this adjustable alternatingvoltage of 0 to 34 volts to autotransformer 244. This autotransformer isprovided to adjust the tensions at each individual winding head and maybe adjusted to supply 0 to 100% of the 0 to 34 alternating voltage oftransformer 24]. to bridge rectifier 245 through protective fuse 246.Bridge rectifier 245 converts this adjustable alternating voltage todirect current voltage adjustable between 0 and 24 volts. The directcurrent is supplied through ammeter 247 and disconnect switch 248 toslip rings 249 and 250. Conductor 251 is connected to the rotatablewinding head at 252 of the machine and is grounded as shown at 253through slip ring 250 to avoid ground current fiow through the rotatableframe support bearings. Conductor 254 carries the adjustable directcurrent voltage to rheostat coils 223 shown in FIG. 13 and connections224 pass such voltage to the magnets 225 of the magnetic brakes 226 ofthe two winding heads of that particular stand.

The magnetic brakes 226 supply a frictional torque to resist the actionof the winding mechanisms in pulling the tape off the tape rolls 209(FIGS. 10, 11 and 12) Which are held rigidly to the spindles 227 of themagnetic brakes 226. Conductors 242 and 243 also supply the adjustableAC voltage by parallel connections to each winding head of the machine.The aforesaid elements 244 through 252, inclusive, are duplicated oneach winder head. Rheostat 223 (FIG. 15) maintains a constant tension onboth tapes as they are being wound regardless of the size of the coil oftape which is rigidly attached to the spindles 227 of the magnetic brake226.

1. THE METHOD OF MAKING A TUBULAR ARTICLE COMPRISING, FORMING A PREFORMBY WINDING A PLURALITY OF LAYERS OF TAPE INDIFFERENT HELICAL DIRECTIONS,SAID TAPE COMPRISING A CARRIER STRIP HAVING ON ONE SIDE THEREOF APLURALITY OF PARALLEL LONGITUDINAL REINFORCING STRANDS WHICH ARESUBSTANTIALLY NONSTRETCHABLE AND A THERMOSETTING BINDER; ENCLOSING SAIDPREFORM WITHIN A PRERIPHERALLY CONFINING MOLD HAVING A LARGER DIAMETERTHAN THE OUTER DIAMETER OF THE PREFORM; INTRODUCING FLUID PRESSURE INTOTHE INTERIOR OF THE PREFORM TO RADIALLY EXPAND THE WALL THEREOF AGAINSTTHE WALL OF THE MOLD AND TO RADIALLY OUTWARDLY COMPRESS THE LAYERS OFTHE PREFORM INTO FIRM CONTACT WITH ONE ANOTHER TO DENSIFY THE PREFORMAND CHANGE THE HELIX ANGLE OF THE HELICALLY WOUND TAPES TO PERMIT SAIDEXPANSION OF THE WALL OF THE PREFORM AND PLACE TH HELICALLY WOUNDREINFORCING STRANDS UNDER EQUAL TENSION; AND HEATING THE PREFORM TOSOFTEN THE BINDER TO REDUCE RESISTANCE TO CHANGE OF THE HELIX ANGLE OFTHE TAPES AND TO CURE THE BINDER; SAID HEAT AND PRESSURE BEING APPLIEDAT LEAST IN PART DURING A COMMON TIME INTERVAL WHICH INCLUDES SAID CUREOF THE BINDER.